The overall object of this project is to understand the mechanism of genome expression in eukaryotic organisms. Whereas much emphasis has been placed on the role of chromatin proteins in controlling gene expression, very little is known about the role of DNA modification in this process. We intend to study DNA methylation in order to ellucidate its biological role. A. The quantitative and qualatiive pattern of in vivo methylation and its relationship to cellular function. b. The localization, characterization and isolation of the active regions of chromatin.